These would include some of the first ever galaxies to form in the Universe and also where the first stars formed.

"We want to see how the first galaxies developed. In astronomy, looking faint, looking far, also means looking far back in time," said Dr Kaufer.

"That is one of the big questions in astronomy - how did the Universe develop."

Back to the beginning

With a 100m telescope, astronomers may have been able to produce images of planets about the same size as Earth circling other stars. But this may be beyond the capabilities of a 42m telescope.

However, it could allow scientists to study the atmospheres of so-called extrasolar planets, looking for the spectral signatures of life such as methane gas and chlorophyll, the pigment used for photosynthesis by plants and cyanobacteria.

Vista will view the skies through infrared wavelengths

Eso officials say construction could begin as early as 2010-11.

But there is still no agreement over where to site the project. Large observatories like the VLT need to be located in remote, dry places with cloud-free skies for best observing conditions.

Sites under discussion include South Africa, Tibet, Morocco, Greenland and Antarctica.

Near to Eso's VLT site in Chile's Atacama desert, a UK-funded large observatory is nearing completion. Vista (Visible and Infrared Survey Telescope for Astronomy) will use infrared wavelengths to detect objects that are too distant or too cool to be seen using the visible spectrum.

The steel structure that will hold Vista's primary mirror in place has now been shipped to Chile and installed inside the telescope enclosure.

Project scientist Jim Emerson said he hoped the first pictures from the telescope will come as early as next summer.